Long-Term Epidural Patching Outcomes and Predictors of Benefit in Patients With Suspected CSF Leak Nonconforming to ICHD-3 Criteria.

BACKGROUND AND OBJECTIVES: Spinal CSF leaks lead to spontaneous intracranial hypotension (SIH). While International Classification of Headache Disorders, Third Edition (ICHD-3) criteria necessitate imaging confirmation or low opening pressure (OP) for SIH diagnosis, their sensitivity may be limited. We offered epidural blood patches (EBPs) to patients with symptoms suggestive of SIH, with and without a documented low OP or confirmed leak on imaging. This study evaluates the efficacy of this strategy. METHODS: We conducted a prospective cohort study with a nested case-control design including all patients who presented to a tertiary headache clinic with clinical symptoms of SIH who completed study measures both before and after receiving an EBP between August 2016 and November 2018. RESULTS: The mean duration of symptoms was 8.7 ± 8.1 years. Of 85 patients assessed, 69 did not meet ICHD-3 criteria for SIH. At an average of 521 days after the initial EBP, this ICHD-3-negative subgroup experienced significant improvements in Patient-Reported Outcomes Measurement Information System (PROMIS) Global Physical Health score of +3.3 (95% CI 1.5-5.1), PROMIS Global Mental Health score of +1.8 (95% CI 0.0-3.5), Headache Impact Test (HIT)-6 head pain score of -3.8 (95% CI -5.7 to -1.8), Neck Disability Index of -4.8 (95% CI -9.0 to -0.6) and PROMIS Fatigue of -2.3 (95% CI -4.1 to -0.6). Fifty-four percent of ICHD-3-negative patients achieved clinically meaningful improvements in PROMIS Global Physical Health and 45% in HIT-6 scores. Pain relief following lying flat prior to treatment was strongly associated with sustained clinically meaningful improvement in global physical health at an average of 521 days (odds ratio 1.39, 95% CI 1.1-1.79; p < 0.003). ICHD-3-positive patients showed high rates of response and previously unreported, treatable levels of fatigue and cognitive deficits. DISCUSSION: Patients who did not conform to the ICHD-3 criteria for SIH showed moderate rates of sustained, clinically meaningful improvements in global physical health, global mental health, neck pain, fatigue, and head pain after EBP therapy. Pre-treatment improvement in head pain when flat was associated with later, sustained improvement after EBP therapy among patients who did not meet the ICHD-3 criteria. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that epidural blood patch is an effective treatment of suspected CSF leak not conforming to ICHD-3 criteria for SIH.

Arterial Spin-Labeling and DSC Perfusion Metrics Improve Agreement in Neuroradiologists' Clinical Interpretations of Posttreatment High-Grade Glioma Surveillance MR Imaging-An Institutional Experience.

BACKGROUND AND PURPOSE: MR perfusion has shown value in the evaluation of posttreatment high-grade gliomas, but few studies have shown its impact on the consistency and confidence of neuroradiologists' interpretation in routine clinical practice. We evaluated the impact of adding MR perfusion metrics to conventional contrast-enhanced MR imaging in posttreatment high-grade glioma surveillance imaging. MATERIALS AND METHODS: This retrospective study included 45 adults with high-grade gliomas who had posttreatment perfusion MR imaging. Four neuroradiologists assigned Brain Tumor Reporting and Data System scores for each examination on the basis of the interpretation of contrast-enhanced MR imaging and then after the addition of arterial spin-labeling-CBF, DSC-relative CBV, and DSC-fractional tumor burden. Interrater agreement and rater agreement with a multidisciplinary consensus group were assessed with κ statistics. Raters used a 5-point Likert scale to report confidence scores. The frequency of clinically meaningful score changes resulting from the addition of each perfusion metric was determined. RESULTS: Interrater agreement was moderate for contrast-enhanced MR imaging alone (κ = 0.63) and higher with perfusion metrics (arterial spin-labeling-CBF, κ = 0.67; DSC-relative CBV, κ = 0.66; DSC-fractional tumor burden, κ = 0.70). Agreement between raters and consensus was highest with DSC-fractional tumor burden (κ = 0.66-0.80). Confidence scores were highest with DSC-fractional tumor burden. Across all raters, the addition of perfusion resulted in clinically meaningful interpretation changes in 2%-20% of patients compared with contrast-enhanced MR imaging alone. CONCLUSIONS: Adding perfusion to contrast-enhanced MR imaging improved interrater agreement, rater agreement with consensus, and rater confidence in the interpretation of posttreatment high-grade glioma MR imaging, with the highest agreement and confidence scores seen with DSC-fractional tumor burden. Perfusion MR imaging also resulted in interpretation changes that could change therapeutic management in up to 20% of patients.

Validation of a deep learning model for traumatic brain injury detection and NIRIS grading on non-contrast CT: a multi-reader study with promising results and opportunities for improvement.

PURPOSE: This study aimed to assess and externally validate the performance of a deep learning (DL) model for the interpretation of non-contrast computed tomography (NCCT) scans of patients with suspicion of traumatic brain injury (TBI). METHODS: This retrospective and multi-reader study included patients with TBI suspicion who were transported to the emergency department and underwent NCCT scans. Eight reviewers, with varying levels of training and experience (two neuroradiology attendings, two neuroradiology fellows, two neuroradiology residents, one neurosurgery attending, and one neurosurgery resident), independently evaluated NCCT head scans. The same scans were evaluated using the version 5.0 of the DL model icobrain tbi. The establishment of the ground truth involved a thorough assessment of all accessible clinical and laboratory data, as well as follow-up imaging studies, including NCCT and magnetic resonance imaging, as a consensus amongst the study reviewers. The outcomes of interest included neuroimaging radiological interpretation system (NIRIS) scores, the presence of midline shift, mass effect, hemorrhagic lesions, hydrocephalus, and severe hydrocephalus, as well as measurements of midline shift and volumes of hemorrhagic lesions. Comparisons using weighted Cohen's kappa coefficient were made. The McNemar test was used to compare the diagnostic performance. Bland-Altman plots were used to compare measurements. RESULTS: One hundred patients were included, with the DL model successfully categorizing 77 scans. The median age for the total group was 48, with the omitted group having a median age of 44.5 and the included group having a median age of 48. The DL model demonstrated moderate agreement with the ground truth, trainees, and attendings. With the DL model's assistance, trainees' agreement with the ground truth improved. The DL model showed high specificity (0.88) and positive predictive value (0.96) in classifying NIRIS scores as 0-2 or 3-4. Trainees and attendings had the highest accuracy (0.95). The DL model's performance in classifying various TBI CT imaging common data elements was comparable to that of trainees and attendings. The average difference for the DL model in quantifying the volume of hemorrhagic lesions was 6.0 mL with a wide 95% confidence interval (CI) of - 68.32 to 80.22, and for midline shift, the average difference was 1.4 mm with a 95% CI of - 3.4 to 6.2. CONCLUSION: While the DL model outperformed trainees in some aspects, attendings' assessments remained superior in most instances. Using the DL model as an assistive tool benefited trainees, improving their NIRIS score agreement with the ground truth. Although the DL model showed high potential in classifying some TBI CT imaging common data elements, further refinement and optimization are necessary to enhance its clinical utility.

Arterial spin labeling clinical applications for brain tumors and tumor treatment complications: A comprehensive case-based review.

Arterial spin labeling (ASL) is a noninvasive neuroimaging technique that allows for quantifying cerebral blood flow without intravenous contrast. Various neurovascular disorders and tumors have cerebral blood flow alterations. Identifying these perfusion changes through ASL can aid in the diagnosis, especially in entities with normal structural imaging. In addition, complications of tumor treatment and tumor progression can also be monitored using ASL. In this case-based review, we demonstrate the clinical applications of ASL in diagnosing and monitoring brain tumors and treatment complications.

Arterial Spin Labeling Imaging Characteristics of Anti-leucine-rich Glioma-Inactivated 1 Encephalitis: A Qualitative and Quantitative Analysis.

Background and Significance: Autoimmune encephalitis (AE) is a rare group of diseases that can present with stroke-like symptoms. Anti-leucine-rich glioma inactivated 1 (LGI1) encephalitis is an AE subtype that is infrequently associated with neoplasms and highly responsive to prompt immunotherapy treatment. Therefore, accurate diagnosis of LGI1 AE is essential in timely patient management. Neuroimaging plays a critical role in evaluating stroke and stroke mimics such as AE. Arterial Spin Labeling (ASL) is an MRI perfusion modality that measures cerebral blood flow (CBF) and is increasingly used in everyday clinical practice for stroke and stroke mimic assessment as a non-contrast sequence. Our goal in this preliminary study is to demonstrate the added value of ASL in detecting LGI1 AE for prompt diagnosis and treatment. Methods: In this retrospective single center study, we identified six patients with seropositive LGI1 AE who underwent baseline MRI with single delay 3D pseudocontinuous ASL (pCASL), including five males and one female between ages 28 and 76 years, with mean age of 55 years. Two neuroradiologists qualitatively interpreted the ASL images by visual inspection of CBF using a two-point scale (increased, decreased) when compared to both the ipsilateral and contralateral unaffected temporal and non-temporal cortex. The primary measures on baseline ASL evaluation were a) presence of ASL signal abnormality, b) if present, signal characterization based on the two-point scale, c) territorial vascular distribution, d) localization, and e) laterality. Quantitative assessment was also performed on postprocessed pCASL cerebral blood flow (CBF) maps. The obtained CBF values were then compared between the affected temporal cortex and each of the unaffected ipsilateral parietal, contralateral temporal, and contralateral parietal cortices. Results: On consensus qualitative assessment, all six patients demonstrated ASL hyperperfusion and corresponding FLAIR hyperintensity in the hippocampus and/or amygdala in a non-territorial distribution (6/6, 100%). The ASL hyperperfusion was found in the right hippocampus or amygdala in 5/6 (83%) of cases. Four of the six patients underwent initial follow-up imaging where all four showed resolution of the initial ASL hyperperfusion. In the same study on structural imaging, all four patients were also diagnosed with mesial temporal sclerosis (MTS). Quantitative assessment was separately performed and demonstrated markedly increased CBF values in the affected temporal cortex (mean, 111.2 ml/min/100 g) compared to the unaffected ipsilateral parietal cortex (mean, 49 ml/min/100 g), contralateral temporal cortex (mean, 58.2 ml/min/100 g), and contralateral parietal cortex (mean, 52.2 ml/min/100 g). Discussion: In this preliminary study of six patients, we demonstrate an ASL hyperperfusion pattern, with a possible predilection for the right mesial temporal lobe on both qualitative and quantitative assessments in patients with seropositive LGI1. Larger scale studies are necessary to further characterize the strength of these associations.

Toxoplasmosis Among 38 751 Hematopoietic Stem-cell Transplant Recipients: A Systematic Review of Disease Prevalence and a Compilation of Imaging and Autopsy Findings.

BACKGROUND: Toxoplasmosis in hematopoietic stem-cell transplant (HSCT) recipients can be life threatening if not promptly diagnosed and treated. METHODS: We performed a systematic review (PubMed last search March 29, 2020) of toxoplasmosis among HSCT recipients and calculated the toxoplasmosis prevalence across studies. We also created a compilation list of brain imaging, chest imaging, and autopsy findings of toxoplasmosis among HSCT recipients. RESULTS: We identified 46 eligible studies (47 datasets) with 399 toxoplasmosis cases among 38 751 HSCT recipients. There was large heterogeneity in the reported toxoplasmosis prevalence across studies, thus formal meta-analysis was not attempted. The median toxoplasmosis prevalence among 38 751 HSCT recipients was 2.14% (range 0%-66.67%). Data on toxoplasmosis among at-risk R+HSCT recipients were more limited (25 studies; 2404 R+HSCT recipients [6.2% of all HSCT recipients]), although the median number of R+HSCT recipients was 56.79% across all HSCT recipients. The median toxoplasmosis prevalence across studies among 2404 R+HSCT was 7.51% (range 0%-80%) versus 0% (range 0%-1.23%) among 7438 R-HSCT. There were limited data to allow meaningful analyses of toxoplasmosis prevalence according to prophylaxis status of R+HSCT recipients. CONCLUSIONS: Toxoplasmosis prevalence among HSCT recipients is underestimated. The majority of studies report toxoplasmosis prevalence among all HSCT recipients rather than only among the at-risk R+HSCT recipients. In fact, the median toxoplasmosis prevalence among all R+//R- HSCT recipients is 3.5-fold lower compared with the prevalence among only the at-risk R+HSCT recipients and the median prevalence among R+HSCT recipients is 7.51-fold higher than among R-HSCT recipients. The imaging findings of toxoplasmosis among HSCT recipients can be atypical. High index of suspicion is needed in R+HSCT recipients with fever, pneumonia, or encephalitis.

Simultaneous time of flight-MRA and T2* imaging for cerebrovascular MRI.

PURPOSE: 3D multi-echo gradient-recalled echo (ME-GRE) can simultaneously generate time-of-flight magnetic resonance angiography (pTOF) in addition to T2*-based susceptibility-weighted images (SWI). We assessed the clinical performance of pTOF generated from a 3D ME-GRE acquisition compared with conventional TOF-MRA (cTOF). METHODS: Eighty consecutive children were retrospectively identified who obtained 3D ME-GRE alongside cTOF. Two blinded readers independently assessed pTOF derived from 3D ME-GRE and compared them with cTOF. A 5-point Likert scale was used to rank lesion conspicuity and to assess for diagnostic confidence. RESULTS: Across 80 pediatric neurovascular pathologies, a similar number of lesions were reported on pTOF and cTOF (43-40%, respectively, p > 0.05). Rating of lesion conspicuity was higher with cTOF (4.5 ± 1.0) as compared with pTOF (4.0 ± 0.7), but this was not significantly different (p = 0.06). Diagnostic confidence was rated higher with cTOF (4.8 ± 0.5) than that of pTOF (3.7 ± 0.6; p < 0.001). Overall, the inter-rater agreement between two readers for lesion count on pTOF was classified as almost perfect (κ = 0.98, 96% CI 0.8-1.0). CONCLUSIONS: In this study, TOF-MRA simultaneously generated in addition to SWI from 3D MR-GRE can serve as a diagnostic adjunct, particularly for proximal vessel disease and when conventional TOF-MRA images are absent.

Spinal cerebrospinal fluid leak in the context of pars interarticularis fracture.

BACKGROUND: Spinal cerebrospinal fluid (CSF) leak can lead to intracranial hypotension and is an important differential diagnosis to consider in patients with sudden-onset chronic daily headaches. Pars interarticularis (PI) fracture is a potential rare cause of suspected spinal CSF leak. METHODS: This is a retrospective case series of 6 patients with suspected spinal CSF leak evaluated between January 2016 and September 2019. All patients received a magnetic resonance imaging (MRI) of the brain with and without gadolinium, MRI whole spine and full spine computed tomography (CT) myelogram. Targeted epidural patches with fibrin sealant were performed. Treatment response at return visit (3 months post-patch) was documented. RESULTS: Six patients (4 females, 2 males) were diagnosed with a suspected spinal CSF leak and PI fracture. Mean age at the time of headache onset was 39 years old, and a range from 32 to 50 years old. Mean time to targeted epidural patches with fibrin sealant was 4.5 years. All 6 patients had PI fractures identified on CT myelogram and received targeted epidural patches with fibrin sealant at the site of the PI fracture. All patients had significant improvement in their headache intensity. CONCLUSION: Our study highlights: 1) the importance of PI fracture as a possible culprit of suspected spinal CSF leak in patients with intracranial hypotension; 2) the added benefit of CT imaging for detecting bony abnormalities such as fractures in patients with intracranial hypotension; and 3) the successful treatment of suspected spinal CSF leak when targeting the fracture site.

A within-coil optical prospective motion-correction system for brain imaging at 7T.

PURPOSE: Motion artifact limits the clinical translation of high-field MR. We present an optical prospective motion correction system for 7 Tesla MRI using a custom-built, within-coil camera to track an optical marker mounted on a subject. METHODS: The camera was constructed to fit between the transmit-receive coils with direct line of sight to a forehead-mounted marker, improving upon prior mouthpiece work at 7 Tesla MRI. We validated the system by acquiring a 3D-IR-FSPGR on a phantom with deliberate motion applied. The same 3D-IR-FSPGR and a 2D gradient echo were then acquired on 7 volunteers, with/without deliberate motion and with/without motion correction. Three neuroradiologists blindly assessed image quality. In 1 subject, an ultrahigh-resolution 2D gradient echo with 4 averages was acquired with motion correction. Four single-average acquisitions were then acquired serially, with the subject allowed to move between acquisitions. A fifth single-average 2D gradient echo was acquired following subject removal and reentry. RESULTS: In both the phantom and human subjects, deliberate and involuntary motion were well corrected. Despite marked levels of motion, high-quality images were produced without spurious artifacts. The quantitative ratings confirmed significant improvements in image quality in the absence and presence of deliberate motion across both acquisitions (P < .001). The system enabled ultrahigh-resolution visualization of the hippocampus during a long scan and robust alignment of serially acquired scans with interspersed movement. CONCLUSION: We demonstrate the use of a within-coil camera to perform optical prospective motion correction and ultrahigh-resolution imaging at 7 Tesla MRI. The setup does not require a mouthpiece, which could improve accessibility of motion correction during 7 Tesla MRI exams.

Interobserver Agreement for the Computed Tomography Severity Grading Scales for Acute Traumatic Brain Injury.

The purpose of this study was to determine the interobserver variability among providers of different specialties and levels of experience across five established computed tomography (CT) scoring systems for acute traumatic brain injury (TBI). One hundred cases were selected at random from a retrospective population of adult patients transported to our emergency department and subjected to a non-contrast head CT due to suspicion of TBI. Eight neuroradiologists and neurosurgeons in trainee (residents and fellows) and attending roles independently scored each non-contrast head CT scan on the Marshall, Rotterdam, Helsinki, Stockholm, and NeuroImaging Radiological Interpretation System (NIRIS) head CT scales. Interobserver variability of scale scores-overall and by specialty and level of training-was quantified using the intraclass correlation coefficient (ICC), and agreement with respect to National Institutes of Health Common Data Elements (NIH CDEs) was assessed using Cohen's kappa. All CT severity scoring systems showed high interobserver agreement as evidenced by high ICCs, ranging from 0.75-0.89. For all scoring systems, neuroradiologists (ICC range from 0.81-0.94) tended to have higher interobserver agreement than neurosurgeons (ICC range from 0.63-0.76). For all scoring systems, attendings (ICC range from 0.76-0.89) had similar interobserver agreement to trainees (ICC range from 0.73-0.89). Agreement with respect to NIH CDEs was high for ascertaining presence/absence of hemorrhage, skull fracture, and mass effect, with estimated kappa statistics of least 0.89. Acute TBI CT scoring systems demonstrate high interobserver agreement. These results provide scientific rigor for future use of these systems for the classification of acute TBI.

A potential new role for ASL perfusion imaging: Diagnosis of metronidazole induced encephalopathy - Two companion cases.

Metronidazole induced encephalopathy (MIE) is a rare condition due to prolonged high dose administration of metronidazole. MIE with corresponding increased perfusion on MRI arterial spin labeling (ASL) of the involved regions of the brain appears not to have been reported in the literature to date. We present two such cases, a 59-year-old male with recurrent C difficile colitis with classic MR imaging characteristics of MIE, and a companion case of a 65-year-old female with gangrenous cholecystitis also presumed to have MIE. Despite aggressive medical management, both patients expired. Our cases demonstrate a correlation with ASL hyperperfusion to affected brain regions thought to be due to edema or inflammation. Perfusion imaging may play a role in diagnosis of MIE.

Ferumoxytol-enhanced MRI for surveillance of pediatric cerebral arteriovenous malformations.

OBJECTIVE: Children with intracranial arteriovenous malformations (AVMs) undergo digital DSA for lesion surveillance following their initial diagnosis. However, DSA carries risks of radiation exposure, particularly for the growing pediatric brain and over lifetime. The authors evaluated whether MRI enhanced with a blood pool ferumoxytol (Fe) contrast agent (Fe-MRI) can be used for surveillance of residual or recurrent AVMs. METHODS: A retrospective cohort was assembled of children with an established AVM diagnosis who underwent surveillance by both DSA and 3-T Fe-MRI from 2014 to 2016. Two neuroradiologists blinded to the DSA results independently assessed Fe-enhanced T1-weighted spoiled gradient recalled acquisition in steady state (Fe-SPGR) scans and, if available, arterial spin labeling (ASL) perfusion scans for residual or recurrent AVMs. Diagnostic confidence was examined using a Likert scale. Sensitivity, specificity, and intermodality reliability were determined using DSA studies as the gold standard. Radiation exposure related to DSA was calculated as total dose area product (TDAP) and effective dose. RESULTS: Fifteen patients were included in this study (mean age 10 years, range 3-15 years). The mean time between the first surveillance DSA and Fe-MRI studies was 17 days (SD 47). Intermodality agreement was excellent between Fe-SPGR and DSA (κ = 1.00) but poor between ASL and DSA (κ = 0.53; 95% CI 0.18-0.89). The sensitivity and specificity for detecting residual AVMs using Fe-SPGR were 100% and 100%, and using ASL they were 72% and 100%, respectively. Radiologists reported overall high diagnostic confidence using Fe-SPGR. On average, patients received two surveillance DSA studies over the study period, which on average equated to a TDAP of 117.2 Gy×cm2 (95% CI 77.2-157.4 Gy×cm2) and an effective dose of 7.8 mSv (95% CI 4.4-8.8 mSv). CONCLUSIONS: Fe-MRI performed similarly to DSA for the surveillance of residual AVMs. Future multicenter studies could further investigate the efficacy of Fe-MRI as a noninvasive alternative to DSA for monitoring AVMs in children.

Imaging Evaluation of the Adult Presenting With New-Onset Seizure.

OBJECTIVE: The purpose of this study is to discuss the evidence supporting the use of neuroimaging in adult patients presenting with new-onset seizure. CONCLUSION: Unenhanced CT should be the initial imaging examination performed for adults presenting with first unprovoked seizure in the acute setting to exclude conditions requiring urgent or emergent intervention. MRI has added benefits and should be considered for adults presenting acutely for whom the initial CT is negative and for those presenting with new-onset seizure in the nonacute setting.

Temporal Bone CT Scan for Malleal Ligaments Assessment.

OBJECTIVE: To determine the feasibility of using temporal bone computed tomography (CT) scans to identify malleal ligaments and the prevalence of calcification in malleal ligaments. STUDY DESIGN: Retrospective case review. CT scans were blindly and retrospectively reviewed by two physicians (a radiologist and a nonradiologist). Scans differed by slice thickness, and included both conventional CT and cone beam CT (CBCT). SETTING: Ambulatory tertiary referral center. PATIENTS: One hundred fifty-one temporal bone CT scans, obtained between the years 2014 and 2017, were initially screened, which included 302 ears. Patients with previous tympanomastoid surgery or middle ear opacification were excluded, leaving 187 ears in the study. INTERVENTION: Diagnostic. MAIN OUTCOME MEASURE: Percentage of visible normal and calcified malleal ligaments. RESULTS: Scans with submillimeter slice thickness were more likely to demonstrate all three malleal ligaments than those with 1 ml and larger slices (83.7% versus 50.0% for nonradiologist, p < 0.0001; 59.6 versus 34.8% for radiologist, p < 0.0001). Calcification was seen in 11.8% of ears reviewed. The ability to detect malleal ligaments with cone beam CT was 86.2%, while the rate with conventional CT was 71.1%, a difference that persisted when controlling for slice thickness. Interobserver agreement for the detection of malleal ligaments was 65% with a Cohen's kappa coefficient of κ = 0.27. CONCLUSION: Visualization of the malleal ligaments using CT scans is feasible in a majority of aerated ears. Detection of malleal ligaments improves with thinner slice thickness and cone-beam technique. Low interobserver agreement suggests the importance of experience and a need for standardized review.

Rapid-sequence brain magnetic resonance imaging for Chiari I abnormality.

OBJECTIVE Fast magnetic resonance imaging (fsMRI) sequences are single-shot spin echo images with fast acquisition times that have replaced CT scans for many conditions. Introduced as a means of evaluating children with hydrocephalus and macrocephaly, these sequences reduce the need for anesthesia and can be more cost-effective, especially for children who require multiple surveillance scans. However, the role of fsMRI has yet to be investigated in evaluating the posterior fossa in patients with Chiari I abnormality (CM-I). The goal of this study was to examine the diagnostic performance of fsMRI in evaluating the cerebellar tonsils in comparison to conventional MRI. METHODS The authors performed a retrospective analysis of 18 pediatric patients with a confirmed diagnosis of CM-I based on gold-standard conventional brain MRI and 30 controls without CM-I who had presented with various neurosurgical conditions. The CM-I patients were included if fsMRI studies had been obtained within 1 year of conventional MRI with no surgical intervention between the studies. Two neuroradiologists reviewed the studies in a blinded fashion to determine the diagnostic performance of fsMRI in detecting CM-I. For the CM-I cohort, the fsMRI and T2-weighted MRI exams were randomized, and the blinded reviewers performed tonsillar measurements on both scans. RESULTS The mean age of the CM-I cohort was 7.39 years, and 50% of these subjects were male. The mean time interval between fsMRI and conventional T2-weighted MRI was 97.8 days. Forty-four percent of the subjects had undergone imaging after posterior fossa decompression. The sensitivity and specificity of fsMRI in detecting CM-I was 100% (95% CI 71.51%-100%) and 92.11% (95% CI 78.62%-98.34%), respectively. If only preoperative patients are considered, both sensitivity and specificity increase to 100%. The authors also performed a cost analysis and determined that fsMRI was significantly cost-effective compared to T2-weighted MRI or CT. CONCLUSIONS Despite known limitations, fsMRI may serve as a useful diagnostic and surveillance tool for CM-I. It is more cost-effective than full conventional brain MRI and decreases the need for sedation in young children.

Vertical diplopia and oscillopsia due to midbrain keyhole aqueduct syndrome associated with severe cough.

PURPOSE: Midline structural defects in the neural axis can give rise to neuro-ophthalmic symptoms. We report a rare case of keyhole aqueduct syndrome presenting after two years of severe cough due to gastroesophageal reflux disease. OBSERVATIONS: A 58-year-old woman with a 2-year history of daily, severe cough presented to the neuro-ophthalmology clinic with progressive diplopia and oscillopsia. Examination revealed a 1-2 Hz down-beating nystagmus in primary gaze that worsened with left, right, and down gazes. Gaze evoked nystagmus and mild paresis were also seen with up gaze. There was an incomitant left hypertropia due to skew deviation that worsened with right and up gazes and improved with down gaze. She also had a right-sided ptosis and a 3 mm anisocoria not due to cranial nerve 3 paresis or Horner's syndrome. Brain magnetic resonance imaging showed a 1.5 mm × 11.7 mm × 6 mm midline cleft in the ventral midbrain communicating with the cerebral aqueduct, consistent with keyhole aqueduct syndrome. Her nystagmus and diplopia improved with oral acetazolamide treatment, at high doses of 2500-3000 mg per day. CONCLUSIONS AND IMPORTANCE: We report the first case of midbrain keyhole aqueduct syndrome with ocular motor and other neuro-ophthalmic manifestations associated with severe cough. Although her cough was effectively treated and intracranial pressure measurement was normal, her ophthalmic symptoms continued to progress, which is common in previous cases reported. Treatment with acetazolamide led to significant improvement, supporting the use of acetazolamide in this rare condition.

Advanced MRI Measures of Cerebral Perfusion and Their Clinical Applications.

Cerebral blood flow measurement by magnetic resonance imaging perfusion (MRP) techniques is broadly applied to patients with acute ischemic stroke, vasospasm following aneurysmal subarachnoid hemorrhage, chronic arterial steno-occlusive disease, cervical atherosclerotic disease, and primary brain neoplasms. MRP may be performed using an exogenous tracer, most commonly gadolinium-based intravenous contrast, or an endogenous tracer, such as arterial spin labeling (ASL) or intravoxel incoherent motion (IVIM). Here, we review the technical basis of commonly performed MRP techniques, the interpretation of MRP imaging maps, and how MRP provides valuable clinical information in the triage of patients with cerebral disease.

Downbeat nystagmus secondary to familial hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis is a rare autosomal recessive disorder characterized by severe inflammation induced by defective natural killer cell function, which triggers a state of highly stimulated but ineffective immune response. This disorder can affect multiple organ systems, and neurologic manifestations include irritability, seizures, impaired consciousness, meningismus, and cranial nerve palsies. We describe a unique case of hemophagocytic lymphohistiocytosis in which downbeat nystagmus developed due to cerebellar swelling with compression of the cervicomedullary junction.